1. Field of the Invention
This invention relates to a process of stalling the speeds of articles to be conveyed in a pneumatic conveying system and a device therefor, and more particularly to a process of stalling the speeds of articles to be conveyed in a pneumatic conveying system and a device therefor, wherein the articles thrown into a transporting piping are conveyed by conveying power wind flowing into the transporting piping.
2. Description of the Related Art
In general, when the articles are conveyed by a pneumatic conveying system through a transporting piping, the articles are discharged at high speed through the outlet of the transporting piping, whereby the articles, undergo great impact so that flaws wear and the like are caused to the articles.
To relieve the impact applied to the articles, there has heretofore been proposed a system as shown in FIG. 5 (Japanese Patent Kokai (Laid-open) No. 153718/1984). This device has a pneumatic tube 1 is formed therein with discharge holes 2 and communicating holes 3. These discharge holes 2 and communicating holes 3 are surrounded by a cover tube 4 and a working head 5, respectively. The cover tube 4 is provided with a fluid exhaust tube 6 having an electromagnetic valve 6A, and the working head 5 is provided with a fluid introducing tube 7 having an electromagnetic valve 7A for ON-OFF operating the flow of compressed air and with a connecting tube 8 branched from this fluid introducing tube 7 and having an exhaust valve 8A and a constant quantity sucking pump 8B. Incidentally, a capsule detecting tube 9 having a flow rate sensor 9A is provided on the tail end face of the pneumatic tube 1.
In this device, the articles are conveyed under pressure of compressed air by the pneumatic tube 1 toward the working head 5, while the electromagnetic valves 6A and 7A are opened to allow compressed air equal to the value of pressure of the conveying compressed air to flow from the electromagnetic valve 7A into the pneumatic tube 1 through the fluid introducing tube 7, the working head 5 and the communicating holes 3. The compressed air is discharged from the electromagnetic valve 6A through the cover tube 4. Pressures of the both compressed airs flowing in the two directions are brought into a balanced state at positions corresponding to the discharge holes 2, whereby the articles to be conveyed are stopped at these positions. Subsequently, when the electromagnetic valves 6A and 7A are closed and the pump 8B is operated to slowly exhaust the compressed air in the working head 5 through the exhaust valve 8A, the balance in the pneumatic tube 1 is lost, whereby the articles are slowly lowered.
In the above-described conventional device, capsules each incorporating therein a sample are made to be articles to be conveyed, these capsules are temporarily stopped at the positions corresponding to the discharge holes 2, and thereafter, slowly moved to the position of the working head 5, thus presenting such disadvantages that the device cannot be applied to the pneumatic conveying system wherein the articles to be conveyed are continuously thrown into the transporting piping for conveying in large quantities, and the device becomes complicated in construction.